My prior U.S. Pat. No. 4,087,206 issued May 2, 1978 also scavenges oil from oil wells extending down into the earth. However, the concept of the present invention uniquely includes collapsible chambers at the outer ends of the power piston with means for preventing the simultaneous collapse of the chambers, such that upon reversal of the power piston when one reversing chamber is collapsed, the opposite chamber is maintained uncollapsed, thereby avoiding energy expenditure in uncollapsing the new forward moving chamber on the opposite or succeeding power stroke. Thus, a much more efficient concept is implemented.
Generally, the recovery system employs a hydraulically operated motor in combination with a fluid pump for insertion into the deep well, where at least the pump is submerged, and fluid is forced down a tubing to power the motor piston, and the pump recovers production fluids on each up and down reciprocal stroke, such that two (2) gallons of production fluid may be pumped to a farm tank for each gallon of operating fluid pumped down to the motor.